search for people who may have come into contact with her. During
her trip, she’d taken at least one bus and three taxis, potentially
interacting with dozens if not hundreds of people. She’d already been
displaying symptoms when she arrived at the hospital; based on the
nature of Ebola transmission, there was a good chance she could
have passed the virus on. Investigators eventually managed to track
down over one hundred of the girl’s contacts and placed them in
quarantine as a precaution. However, none of them came down with
Ebola. Despite her long journey, the girl hadn’t infected anyone.[69]
When Ebola superspreading events did occur during 2014–15, our
team noticed there was one feature that stood out. Unfortunately, it
wasn’t a particularly helpful one: the cases most likely to be involved
in superspreading were the ones that couldn’t be linked to existing
chains of transmission. Put simply, the people driving the epidemic
were generally the ones the health authorities didn’t know about.
These people went undetected until they sparked a new set of
infections, making it near impossible to predict superspreading
events.[70]
With enough effort, we can often trace some of the path of
infection during an outbreak, reconstructing who might have infected
whom. It can be tempting to construct a narrative as well, speculating
about why certain people transmitted more than others. However, just
because an infection is capable of superspreading doesn’t
necessarily mean the same people are always the superspreaders.
Two people might behave in almost the same way, but by chance one
of them spreads infection and the other does not. When history is
written, one is blamed and the other ignored. Philosophers call it
‘moral luck’: the idea that we tend to view actions with unfortunate
consequences as worse than equal actions without any
repercussions.[71]
Sometimes the people involved in an outbreak do behave
differently, but not necessarily in the way we might assume. In his
book The Tipping Point, Malcolm Gladwell describes an outbreak of
gonorrhea in Colorado Springs, Colorado, during 1981. As part of the
outbreak investigation, epidemiologist John Potterat and his
colleagues had interviewed 769 cases, asking whom they’d recently